ABSTRACT Evaluating the VHF surveillance system in Nigeria The implementation of the integrated disease surveillance and response (IDSR) framework has been fraught with recurring constraints culminating in a weakened health system with sub-optimal emergency response plan when the action threshold for these diseases are reached. AIDRAN project aims to evaluate the performance of the VHF surveillance system (focus on Lassa and Yellow fever) within the IDSR framework to identify pertinent gaps in the system and provide practical applications to improve surveillance practice in the country. The VHF surveillance system evaluation study is a component of the AIDRAN project, the general objective of which is to conduct high quality public health research with focus on epidemiologic, clinical, and laboratory-based projects, surveillance, and research of infectious diseases and other important diseases as well as other public health threats of local importance in Nigeria. The VHF Surveillance system evaluation is a process and outcome evaluation with a mixed methods study design. The evaluation will adopt a two-stage process which includes a preliminary review of existing Lassa and Yellow fever epidemiological and laboratory data followed by a field evaluation. Multi-stage sampling will be used to select twelve health facilities in two urban Local Government Areas (LGAs) and six health facilities in two rural LGAs stratified across the three tiers of health system and by public-private ownership. Quantitative data will be collected using structured electronic tools and analyzed using STATA 15. A key informant interview will be conducted in each of the four LGAs. Qualitative data will be analyzed using MAXQDA 2018. The measurement outcomes of this study will be credible evidence gathered on the performance of the VHF surveillance system based on assessment of defined system attributes. Applicable recommendations to strengthen the system attributes will be proposed.